Coal beds often contain hydrocarbon gases in which a main component is methane. However, production of the methane utilizing wells drilled into the coal beds relies on desorption of the methane from surfaces of solid coal forming a matrix system of the coal bed. Past techniques to recover the methane remove water from open fractures forming a cleat system extending through the coal beds such that with the removal of the water the methane desorbs due to subsequent pressure reduction. In contrast to such desorption processes to recover the methane already present in the coal bed, other methods convert the coal in-situ to produce hydrocarbons based on pyrolysis of the coal.
The methane that desorbs flows through the cleat system to the wells for recovery. Once the water is removed, limited permeability of the cleat system and slow or incomplete desorption results in some of the methane being trapped and unrecovered. Recovery levels may still fail to be economical or reach maximum achievable quantities even with various different prior approaches that attempt to enhance total recovery of the methane and that may be implemented after this initial dewatering and primary recovery of the methane.
Therefore, a need exists for improved methods of recovering coal bed methane.